Datasheet MAX866, MAX867 (Maxim) - 8

3.3V/5V or Adjustable-Output, Single-Cell DC-DC Converters Voltage Reference __________________Design Procedure
The precision voltage reference is suitable for driving external loads, such as an analog-to-digital converter.
Output Voltage Selection
The voltage-reference output changes less than ±2% For the MAX866, you can select a 3.3V or 5V output volt- when sourcing up to 250µA and sinking up to 20µA. If age under logic control, or by tying 3/5 to GND or OUT. the reference drives an external load, bypass it with The MAX867’s output voltage is set by two resistors, R1 0.22µF to GND. If the reference is unloaded, bypass it and R2 (Figure 2b), which form a voltage divider with at least 0.1µF. between the output and FB. Use the following equation to determine the output voltage:
Logic Inputs and Outputs
The 3/5 input is internally diode clamped to GND and R1 + R2 OUT, and should not be connected to signals outside VOUT = VREF ( ________ ) this range. The SHDN input and LBO output (open- R2 drain) are not clamped to V+ and can be pulled as high where V as 7V regardless of the voltage at OUT REF = 1.25V. .
Do not leave control inputs (3/5, LBI, or SHDN) floating.
To simplify resistor selection:
MAX866/MAX867
VOUT R1 = R2 ( _____ - 1) VREF VIN VIN C1 C1 47µF 47µF L1 L1 330µH 330µF D1 D1 5 8 VOUT 5 8 VOUT LBI LX LBI LX C2 C2 MAX866 MAX867 6 R1 47µF 6 R1 47µF OUT OUT 1 2 1 2 SHDN 3/5 OUTPUT SHDN FB SELECT 3 4 3 4 REF LBO REF LBO C3 C3 R2 GND GND 0.1µF 0.1µF 7 7 L1 = COILCRAFT DO1608-334 L1 = COILCRAFT DO1608-334 D1 = MOTOROLA MBR0520LTI D1 = MOTOROLA MBR0520LTI Figure 2a. Standard Application Circuit—Preset Output Figure 2b. Standard Application Circuit—Adjustable Output Voltage Voltage
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